If weakness comes on suddenly and affects one side of the body — face, arm, or leg — call 911 immediately. That is a stroke until proven otherwise, and treatment is measured in minutes. General, whole-body tiredness that has built over weeks is a different problem entirely and belongs in a clinic, not an emergency room.
The distinction between *focal* weakness and *generalised* fatigue is the most important thing in this article, because the two are often described with the same word and they could not be more different in urgency.
First: is it a stroke?
Use FAST:
- F — Face. Ask them to smile. Does one side droop?
- A — Arms. Ask them to raise both arms. Does one drift down?
- S — Speech. Ask them to repeat a simple sentence. Is it slurred or strange?
- T — Time. Any one of these, call 911 now and note the time symptoms started.
Also treat as an emergency: sudden numbness on one side, sudden confusion or trouble understanding speech, sudden vision loss in one or both eyes, sudden severe unexplained headache, or sudden loss of balance and coordination.
Note the time. The clot-dissolving treatments that reverse strokes work within a limited window, and the first question the hospital team will ask is when symptoms began. If someone wakes with symptoms, the relevant time is when they were last known to be well.
Do not drive them. Do not give aspirin — some strokes are bleeds, and aspirin makes those worse. Call 911.
Other weakness that needs emergency care today
- Weakness with chest pain, breathlessness, or sweating — can be a heart attack, particularly in women and people with diabetes
- Weakness with a very high or very low blood sugar in someone with diabetes
- Rapidly progressive weakness, especially starting in the feet and moving upward, or affecting breathing or swallowing
- Weakness after a fall or head injury
- Weakness with a fever and confusion — possible serious infection or sepsis
- Weakness with black or bloody stools, or vomiting blood — bleeding causing anaemia
- Fainting, or near-fainting, particularly on exertion
- Weakness with a very fast, very slow, or irregular heartbeat
- Sudden weakness in heat with no sweating, confusion, or a high temperature — heat stroke
Causes of genuine, gradual fatigue
If none of the above applies and you are simply exhausted in a way that is new and unexplained, there is usually a findable reason. The common ones:
Anaemia — iron deficiency is the most frequent, and in adults it needs a cause found, not just iron prescribed. Heavy periods, gastrointestinal blood loss, and poor absorption are the usual suspects. Breathlessness on stairs and pallor often accompany it.
Thyroid disease — an underactive thyroid causes fatigue, weight gain, cold intolerance, dry skin, and low mood; an overactive one causes fatigue with weight loss, palpitations, and heat intolerance. Both are diagnosed with a simple blood test and both are very treatable.
Diabetes or pre-diabetes — fatigue, thirst, frequent urination, blurred vision.
Sleep apnoea — waking unrefreshed however long you sleep, snoring, witnessed pauses in breathing, daytime sleepiness. Common, under-diagnosed, and a genuine cardiovascular risk factor.
Depression and anxiety — fatigue is a core physical symptom, not a character flaw. Worth naming because people often present with the tiredness and omit the mood.
Medication side effects — beta blockers, antihistamines, some blood pressure drugs, sedatives, and statins in some people. Always worth reviewing, and easy to fix.
Vitamin B12 or vitamin D deficiency — both common, both measurable, both simple to correct. B12 deficiency can also cause tingling and balance problems.
Chronic kidney or liver disease, heart failure, infection — including lingering viral illness, and locally, Valley fever, which characteristically causes weeks of fatigue, cough, and low-grade fever that does not respond to routine antibiotics.
Dehydration and heat strain — in an Arizona summer, this is a genuinely common explanation for new fatigue, and one of the simplest to correct.
The Arizona overlay
Three local patterns we see repeatedly.
Summer fatigue is real. Living and working through months of extreme heat imposes a continuous physiological load. Plenty of people feel flattened from June to September and assume something is wrong with them. Often the answer is fluid, electrolytes, sleep, and avoiding midday exertion — but it is worth a blood test to be sure rather than assuming.
Valley fever. If your fatigue followed a chest infection, or came with a cough and night sweats that have dragged on for more than a few weeks, ask specifically about coccidioidomycosis testing. It is endemic here and frequently missed.
Seasonal residents arriving with no records. If you have just arrived for the season and feel unwell, we have no baseline for you. A first clinic visit that establishes your normal blood counts and thyroid function makes every subsequent problem far easier to interpret.
What a proper fatigue workup looks like
Fatigue is one of the best reasons to see a primary care clinician rather than an emergency physician, because it needs an unhurried, systematic look. At our Medical Clinic that typically means:
- A full history — sleep, mood, diet, alcohol, medication, and what changed and when
- Physical examination, including thyroid, heart, lungs, and lymph nodes
- Blood work drawn and run in this building: blood count, iron studies, thyroid function, blood sugar or HbA1c, kidney and liver function, vitamin B12 and vitamin D, inflammatory markers
- Valley fever testing where the picture fits
- Screening for sleep apnoea and for depression
- A medication review
Most results come back the same day, because the laboratory is on site.
Come with notes. When it started, how it has changed, how you sleep, what you have stopped doing because of it. Vague fatigue is hard to investigate; described fatigue is much easier.
Where to go
Call 911 for any sudden one-sided weakness, face droop, speech difficulty, vision loss, or collapse — and note the time it began.
Come to our Emergency Room — 9700 N. Saguaro Blvd, open 24 hours, no appointment — for weakness with chest pain, fever and confusion, rapidly worsening weakness, signs of bleeding, or fainting. ER: (602) 671-7990.
Book our Medical Clinic for fatigue that has developed over weeks or months without red flags. Call (602) 671-7981.
Related reading
- Your Thyroid: The Symptoms People Blame on Everything Else
- When Counting Sheep Isn’t Enough: Insomnia and Sleep Apnoea
- Prediabetes and Diabetes: The Window Where It’s Still Reversible
Sources
- American Stroke Association — Stroke symptoms and FAST
- CDC — Stroke signs and symptoms
- Mayo Clinic — Fatigue: causes
- CDC — Valley fever